Abstract: There are three classical problems at the chromosome level in cytogenetics, namely the formation mechanisms and effects of Barr body, polytenic chromosome, and lampbrush chromosome. Teachers and researchers keep sustaining attention to the Barr body because of the relationships between Barr body and the X chromosome dosage compensation effect in mammals, the human sex identification, and some human diseases. In our genetics teaching practice, we tried the case-based teaching method. We introduced the classical problems and research progress of the Barr body, as a line, into partial sections of our genetics teaching contents such as sex-linked genetic analysis, eukaryotic gene expression regulation, cancer genetic analysis, and genetic experiments. Finally, it will form a comprehensive summary of related knowledge of genetics through class discussion on the Barr body. We found that this teaching method can not only optimize the teaching contents of genetics, consolidate and widen students' basic knowledge, and help student to form the systemic and developmental views of a classical genetics problem, but also inspire students’ interest in life sciences. Good teaching results have been achieved.

Key words: genetics, cytogenetics, Barr body, research progress, case-based teaching